Method and apparatus for preventing stagnation in fluid reservoirs

ABSTRACT

An apparatus ( 16 ) for preventing stagnation in a fluid reservoir ( 2 ) comprised of: an inlet/outlet conduit ( 6 ); a manifold ( 8 ), which communicates the inlet/outlet conduit ( 6 ) to inlet check valves ( 10 ) and outlet check valves ( 12 ); the inlet check valves ( 10 ) being positioned on the manifold ( 8 ) and being oriented such that a fluid ( 14 ) will flow from the manifold ( 8 ) through the inlet check valves ( 10 ) to the reservoir ( 2 ) during reservoir filling and fluid flow is prevented through the inlet check valves ( 10 ) during reservoir draining; and the outlet check valves ( 12 ) being positioned on the manifold ( 8 ) and spaced from the inlet check valves ( 10 ) to provide fluid flow within the reservoir ( 2 ) in the general direction from the inlet check valves ( 10 ) to the outlet check valves ( 12 ), the outlet check valves ( 12 ) being oriented such that fluid flows from the reservoir ( 2 ) through the outlet check valves ( 12 ) into the manifold ( 8 ) during reservoir draining and fluid flow through the outlet check valves ( 12 ) is prevented during reservoir filling.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to systems for preventing thestagnation of fluids stored in large reservoirs.

[0003] 2. Description of the Prior Art

[0004] Fluid reservoirs, particularly those used to store potable water,have historically had to contend with stagnation problems. Stagnation insuch conventional potable water reservoir systems is a function of thesize of the reservoir and, in particular, the relative dimensions of thecross-sectional area of the reservoir in plan view coupled with thenumber and location of inlet and outlet pipes. Conventional reservoirsare typically filled and drained from a single pipe located at one endof the reservoir. Filling and draining fluids through such a single pipeor conduit creates very little turbulence, particularly in areas withinthe reservoir remote from the inlet/outlet conduit.

[0005] In potable water reservoirs, water may not mix or be “turnedover” in those areas remote from the inlet/outlet conduit. This isreferred to as stagnant water. Potable water is typically “chlorinated”through the addition of hypochlorite or “chlorine” as a disinfectant toprevent microbial growth in the water. The chlorine concentration willdecrease in stagnant water over time, resulting in unsanitary waterquality if a sufficient degree of mixing between influent water andreservoir water is not maintained.

[0006] To a large extent, the fluid added to a reservoir through asingle inlet/outlet conduit remains near the single pipe and is removedfirst during drainage operations, while the fluid previously in thereservoir remains. This phenomenon is generally referred to as“short-circuiting.” Short-circuiting is the continual recirculation ofthe freshest water near the inlet/outlet conduit. Water outside of thisarea of influence becomes stagnant and loses disinfectant residual.

[0007] The prior art recognizes that the use of a plurality of inlet andoutlet pipes would increase the mixing of fluids stored in reservoirs.However, the retrofitting of existing reservoirs to include additionalinlet and outlet conduits can be quite expensive. The prior art alsorecognizes the use of reservoirs having a circular cross-section in planview in an attempt to increase fluid mixing and eliminate “dead zones”that typically occur in the remote corners of reservoirs havingrectangular cross-sections. However, fluid stagnation problems can stillexist even if these improvements are deployed in conventional reservoirsystems.

[0008] U.S. Pat. No. 6,016,839 to Raftis et al. discloses an airdiffuser system for use in wastewater treatment that includes a manifoldand a plurality of elastomeric “duckbill” check valves. The purpose ofthe air diffuser system is to inject and diffuse one process fluid intoanother process fluid for the purpose of aeration, diffusion, agitation,or mixing. The system is particularly well suited for activated sludgeapplications. However, the system does not employ duckbill check valvesoriented to allow fluid to drain from the reservoir into the samemanifold and inlet conduit by which it entered. Moreover, the Raftis etal. patent specifically discloses the benefits of using such “duckbill”check valves to prevent fluids stored within a reservoir from reachingthe manifold.

[0009] There remains a need for an apparatus to minimize or eliminateshort-circuiting, “dead zones,” and/or stagnant areas in large,fluid-containing reservoirs, especially where the reservoirs containpotable water.

SUMMARY OF THE INVENTION

[0010] The present invention provides a system that can be installed inor retrofitted to conventional fluid reservoir systems, which includes amanifold conduit in combination with check valves to encourage crossflowand mixing of fluids stored within the reservoir to reduce, minimize, oreliminate stagnation of the fluid. These anti-stagnation systems can bedeployed in reservoirs of any plan view, cross-sectional shape byadapting the shape of the manifold to the particular shape of thereservoir in which the system is to be installed. Anti-stagnationsystems, according to the present invention, are less expensive thanretrofitting existing reservoirs with multiple inlet and outletconduits.

[0011] The apparatus for preventing stagnation in a fluid reservoir ofthe present invention is comprised of: an inlet/outlet conduit; amanifold which communicates the inlet/outlet conduit to inlet checkvalves and outlet check valves, the inlet check valves being positionedon the manifold and being oriented such that a fluid will flow from themanifold through the inlet check valves to the reservoir duringreservoir filling, and fluid flow is prevented through the inlet checkvalves during reservoir draining, and the outlet check valves beingpositioned on the manifold and spaced from the inlet check valves toprovide fluid flow within the reservoir in the general direction fromthe inlet check valves to the outlet check valves, the outlet checkvalves being oriented such that fluid flows from the reservoir throughthe outlet check valves into the manifold during reservoir draining, andfluid flow through the outlet check valves is prevented during reservoirfilling.

[0012] The present invention is also directed to a method of preventingstagnation in fluid reservoirs. The method generally involves the stepsof: introducing an influent liquid, typically potable water, processwater, or wastewater, to a filling area of a reservoir for storingliquids; withdrawing the liquid from a draining area of the reservoirfor storing liquids, wherein the draining area is remotely located fromthe filling area, such that the influent liquid mixes with the liquid inthe reservoir and the liquid in the reservoir generally flows from thefilling area to the draining area; and expelling the liquid from thedraining area.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 shows a plan view of a rectangular fluid reservoir having asingle inlet/outlet conduit with a U-shaped anti-stagnation systemaccording to the present invention;

[0014]FIG. 2 shows a plan view of a rectangular fluid reservoir having asingle inlet/outlet conduit with an I-shaped anti-stagnation systemaccording to the present invention;

[0015]FIG. 3 shows a plan view of a fluid reservoir of a circularcross-section having a single inlet/outlet conduit with a horizontalanti-stagnation system according present to the invention;

[0016]FIG. 4 shows a perspective view of a standpipe fluid reservoir ofa circular cross-section having a single inlet/outlet conduit with avertical anti-stagnation system according to the invention;

[0017]FIG. 5 shows a front elevational view of two outlet duckbill checkvalves according to the present invention; and

[0018]FIG. 6 shows a front elevational view of two inlet duckbill checkvalves having an upward orientation to facilitate fluid mixing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0019] For the purpose of the description hereinafter, the terms“upper,” “lower,” “right,” “left,” “vertical,” “horizontal,” “top,”“bottom,” and derivatives thereof, shall relate to the invention asoriented in the drawing Figures. However, it is to be understood thatthe invention may assume alternate variations and step sequences exceptwhere expressly specified to the contrary. It is also to be understoodthat the specific devices and processes, illustrated in the attacheddrawings and described in the following specification, is an exemplaryembodiment of the present invention. Hence, specific dimensions andother physical characteristics related to the embodiment disclosedherein are not to be considered as limiting the invention.

[0020]FIG. 1 shows a plan view of a U-shaped anti-stagnation apparatus16 within a fluid reservoir 2 of rectangular shape. A fluid 14,typically potable water, process water, or wastewater, enters and exits(sequentially, not simultaneously) fluid reservoir 2 by way of aninlet/outlet conduit 6. The fluid 14 is retained within fluid reservoir2 by a fluid reservoir wall 4. The fluid reservoir 2 is filled bypumping fluid 14 into inlet/outlet conduit 6. Fluid 14 flows throughinlet/outlet conduit 6 and into a manifold 8, which is connectedthereto. The fluid 14 travels along manifold 8 to one or more inletcheck valves 10, which are preferably a duckbill-type check valve, andfrom there into fluid reservoir 2 for mixing and storage. The preferredduckbill inlet check valves 10 are constructed to perform as bothnon-return valves and nozzles that increase fluid velocity and enhancethe turbulence of mixing of the fluid 14 within fluid reservoir 2. Theduckbill check valves 10 are typically of an elastomeric composition,which reduces maintenance costs related to the use of theanti-stagnation apparatus 16 of the present invention.

[0021] While fluid may flow through manifold 8 to one or more outletcheck valves 12, the fluid 14 is prevented from flowing through outletcheck valve 12 and into fluid reservoir 2 because of the non-returnnature and orientation of outlet check valve 12.

[0022] Draining of fluid reservoir 2 occurs when the hydraulic pressureof the fluid 14, within fluid reservoir 2, is greater than the pressureof the fluid 14 within manifold 8. Under such circumstances, fluid 14flows from fluid reservoir 2 through one or more outlet check valves 12into manifold 8, which is connected to inlet/outlet conduit 6. It ispreferred that outlet check valve 12 be a duckbill-type check valve. Theduckbill check valves 12 are typically of an elastomeric composition asdescribed above.

[0023] Accordingly, anti-stagnation apparatus 16 can be connected to asingle existing inlet/outlet conduit 6 and promotes the thorough mixingof the fluid 14 contained within fluid reservoir 2 by significantlyincreasing the number of locations within fluid reservoir 2 at whichfluid 14 enters and exits the fluid reservoir 2, and by increasing thevelocity by which fluid 14 enters the fluid reservoir 2. By tailoringthe number and spacial orientation of inlet check valves 10 and outletcheck valves 12, fluid 14 is forced to travel throughout fluid reservoir2 during the course of operating the reservoir 2 for its intendedpurpose. By using anti-stagnation apparatus 16, thorough mixing occurs,eliminating (or at least reducing the number of) “dead zones” in areasremote from a single inlet/outlet conduit 6.

[0024] Similarly, FIG. 2 shows an I-shaped shaped anti-stagnationapparatus 17 within a fluid reservoir 2 of rectangular shape. Operationof I-shaped anti-stagnation apparatus 17 is similar to that describedfor U-shaped anti-stagnation apparatus 16. Filing is accomplished asfluid 14 enters inlet/outlet conduit 6, traverses manifold 8 and entersreservoir 2 via inlet check valves 10 aligned along far branch 50 ofmanifold 8. Draining is accomplished as fluid 14 enters outlet checkvalves 12, flows through near branch 51 and exits manifold 8 throughinlet/outlet conduit 6.

[0025]FIG. 3 shows a plan view of a second fluid reservoir 20 having acircular cross-section. Fluid 32 is contained within second fluidreservoir 20 by second fluid reservoir wall 22 and enters and exitssecond fluid reservoir 20 via inlet/outlet conduit 24. Horizontalanti-stagnation apparatus 34 is shown connected to inlet/outlet conduit24. Anti-stagnation apparatus 34 consists of manifold 26, one or moreinlet check valves 28 and one or more outlet check valves 30.

[0026] To fill second fluid reservoir 20, fluid 32 is pumped intoinlet/outlet conduit 24. Fluid 32 flows through inlet/outlet conduit 24and into manifold 26. Fluid flows from manifold 26 and into second fluidreservoir 20 through one or more inlet check valves 28. Inlet checkvalves 28 provide two functions. First, inlet check valves 28 act asnon-return valves. Second, inlet check valves 28 increase the velocityof fluid 32 exiting inlet check valves 28 into second fluid reservoir20. Inlet check valves 28 are preferably a duckbill-type check valve.The non-return nature of outlet check valves 30 prevents fluid 32 fromflowing through manifold 26 and into second fluid reservoir 20 by way ofoutlet check valves 30.

[0027] Second fluid reservoir 20 is drained when the hydraulic pressurewithin second fluid reservoir 20 is greater than the fluid pressurewithin manifold 26. Under such conditions, fluid 32 flows from secondfluid reservoir 20 through one or more outlet check valves 30 intomanifold 26, which is connected to inlet/outlet conduit 24. Thenon-return nature of inlet check valves 28 prevents fluid from flowingfrom second fluid reservoir 20 into manifold 26 through inlet checkvalves 28 during draining of second fluid reservoir 20. Outlet checkvalves 30 are preferably duckbill-type check valves.

[0028] When using anti-stagnation apparatus 34, fluid 32 becomesthoroughly mixed within second fluid reservoir 20 because of the numberof locations through which fluid can enter or exit second fluidreservoir 20 and the relationship between the locations of one or moreinlet check valves 28, one or more outlet check valves 30, and thecross-sectional shape of second fluid reservoir 20. The advantageousmixing is achieved while continuing to use only one inlet/outlet conduit24 on fluid reservoir 20.

[0029]FIG. 4 shows a standpipe fluid reservoir 35, which includes avertical anti-stagnation apparatus 54. Fluid 32 is contained withinstandpipe fluid reservoir 35 by fluid reservoir wall 22 and enters andexits standpipe fluid reservoir 35 via inlet/outlet conduit 24. Verticalanti-stagnation apparatus 54 is shown connected to inlet/outlet conduit24. Vertical anti-stagnation apparatus 54 consists of manifold 26, oneor more inlet check valves 28, and one or more outlet check valves 30.

[0030] To fill standpipe fluid reservoir 35, fluid 32 is pumped intoinlet/outlet conduit 24. Fluid 32 flows through inlet/outlet conduit 24and into manifold 26. A dividing line 57 is an imaginary line separatingstandpipe fluid reservoir 35 into an upper half 58 and a lower half 59.Fluid flows from manifold 26 and into standpipe fluid reservoir 35through one or more inlet check valves 28. Inlet check valves 28 arelocated in upper half 58 of standpipe fluid reservoir 35.

[0031] Standpipe fluid reservoir 35 is drained when fluid 32 flowsthrough one or more outlet check valves 30 into manifold 26, which isconnected to inlet/outlet conduit 24. Outlet check valves 30 are locatedin lower half 59 of standpipe fluid reservoir 35. Overall operation ofstandpipe fluid reservoir 35 is similar to second fluid reservoir 20.

[0032] In general, the use of a horizontal anti-stagnation apparatus,such as those depicted in FIGS. 1, 2, and 3 (anti-stagnation apparatuses16, 17, and 34), instead of vertical anti-stagnation apparatus 54 willbe determined depending on the surface area or diameter 52 (FIG. 4)compared to the height 53 of a fluid reservoir. When the surface areaand/or diameter compared to the height of a fluid reservoir is large,then a horizontal anti-stagnation apparatus will be used, as this designwill provide better stagnation prevention (side to side mixing). Whenthe surface area and/or diameter compared to the height of a fluidreservoir is small (as in a standpipe), then a vertical anti-stagnationapparatus will be used, as this design will provide better stagnationprevention (top to bottom mixing).

[0033] A horizontal anti-stagnation apparatus 34 will typically be usedwhen the ratio of the surface area 52 to the height 53 of the fluidreservoir 22 is greater than 2. In this situation, the apparatus forpreventing stagnation 34 is in a horizontal configuration where theinlet/outlet conduit 24, the manifold 26, the inlet check valves 28, andthe outlet check valves 30 are approximately in a plane parallel tofluid surface 21.

[0034] A vertical anti-stagnation apparatus 54 will typically be usedwhen the ratio of the surface area 52 to the height 53 of the fluidreservoir is less than 1. In this situation, the apparatus forpreventing stagnation 54 is in a vertical configuration where theinlet/outlet conduit 24, the manifold 26, the inlet check valves 28, andthe outlet check valves 30 are approximately in a plane perpendicular tothe fluid surface 21. Generally, the inlet check valves 28 will belocated in the upper half 58 of the fluid reservoir 22, and the outletcheck valves 30 will be located in the lower half 59 of the fluidreservoir 22.

[0035]FIG. 5 shows a pair of the preferred outlet duckbill check valves30, directed into manifold 26 of FIG. 2. As indicated by the arrows,fluid 32 enters outlet duckbill check valves 30 and flows into manifold26 during draining operations of second fluid reservoir 20, as depictedin FIG. 2.

[0036]FIG. 6 shows a pair of the preferred inlet duckbill check valves28 as depicted in FIG. 2. Fluid flows from manifold 26 through inletduckbill check valves 28 in the direction indicated by the arrows. FIG.4 specifically shows inlet duckbill check valves 28 configured in anupward orientation relative to manifold 26. This orientation increasesthe mixing characteristics of the anti-stagnation apparatus 34 bydirecting fluid 32 upward to mix with fluid 32 already present in secondfluid reservoir 20.

[0037] The anti-stagnation apparatus of the present invention can beconnected to the existing inlet/outlet conduit of any conventional fluidreservoir, particularly those designed to store potable water. Theanti-stagnation apparatus of the present invention can be connected tothe inlet/outlet conduit of the conventional fluid reservoir systemusing a suitable mechanical or chemical means. By varying the number andlocation of inlet and outlet check valves, the shape of the manifold,and the orientation of the check valve relative to the manifold, anefficient anti-stagnation apparatus having little or no maintenancerequirements may be created. Hence, the anti-stagnation apparatus of thepresent invention can be adapted for use in reservoirs of shallow depthas well as those that are quite deep. As an example, if a reservoir werea 10 foot diameter tank that was 100 feet high, with a singleinlet/outlet conduit, the anti-stagnation apparatus of the presentinvention can be adapted to ensure that the fluid at the top, or at anyother depth, does not stagnate. In other words, although theanti-stagnation apparatus is depicted in two dimensions, it can beconfigured to prevent fluid stagnation in three dimensions or in anyarea of a fluid reservoir.

[0038] Operation of the conventional fluid reservoir is achieved by theuse of pumps and valves hydraulically connected with a single reservoirinlet/outlet conduit. Such single reservoir inlet/outlet operationapparatuses are typically in place at existing reservoirs. The reservoiroperates based on the relative pressures between the fluid within themanifold and the fluid within the fluid reservoir. Thus, fluid flowsinto the fluid reservoir when the pressure within the manifold isgreater and fluid flows out of the reservoir when the pressure withinthe reservoir is greater. The construction and non-return nature of theinlet and outlet check valves either permit or prevent the flow offluids through them depending on their orientation and the hydraulicpressures which are placed upon them. It should be apparent to oneskilled in the art that the deployment of the anti-stagnation apparatusof the present invention significantly increases the mixing of thefluids during the operation of a fluid reservoir while still beingconnected to a single inlet/outlet conduit.

[0039] Additionally, when, the anti-stagnation apparatus deploysduckbill check valves of elastomeric composition, maintenance costsrelated to the use of the anti-stagnation apparatus are drasticallyreduced. Any suitable elastomeric composition may be used in theduckbill check valves of the present invention. Examples of suitableelastomeric composition that can be used in the duckbill check valvesinclude, but are not limited to, polyolefin elastomer, hydrocarbonrubber elastomer, chlorosulfonated polyethylene elastomer, chlorinatedpolyethylene elastomer, neoprene, neoprene polychloroprene,perfluoroelastomers, fluoroelastomers, silicone rubber, syntheticrubber, and natural rubber.

[0040] The present invention also provides a method for preventingstagnation in fluid reservoirs. The method of the present inventiongenerally includes the steps of: introducing an influent fluid,typically potable water, process water, or wastewater, to afluid-containing reservoir through an inlet/outlet conduit to one ormore inlet check valves; regulating the flow of influent fluid throughthe inlet check valves such that the influent fluid flows from theinlet/outlet conduit through the inlet check valves and into thereservoir when filling is desired and preventing the flow of influentfluid when draining is desired; mixing the influent fluid into the fluidin the reservoir; directing the flow of fluid in the reservoir from theinlet check valves to one or more outlet check valves; regulating theflow of reservoir fluid through the outlet check valves such that theexiting fluid flows from the reservoir through the outlet check valvesto the inlet/outlet conduit when draining is desired and preventing theflow of reservoir fluid through the outlet check valves when filling isdesired; and expelling fluid from the inlet/outlet conduit.

[0041] In a preferred embodiment of the method for preventing stagnationin fluid reservoirs, the inlet check valves are a duckbill-type,oriented to regulate fluid flow as described above, and the outlet checkvalves are a duckbill-type, oriented to regulate fluid flow as describedabove. The preferred duckbill check valves preferably are of anelastomeric composition.

[0042] The present invention has been described with reference tospecific details of particular embodiments thereof. Obviousmodifications and alterations will occur to others upon reading andunderstanding the preceding detailed description. It is not intendedthat such details be regarded as limitations upon the scope of theinvention except insofar as and to the extent that they are included inthe accompanying claims.

We claim:
 1. An apparatus for preventing stagnation in a fluid reservoircomprising: (a) an inlet/outlet conduit through which fluid sequentiallyenters and exits the fluid reservoir; (b) a manifold which sequentiallyconveys the fluid to and from the inlet/outlet conduit; (c) a pluralityof inlet check valves positioned in a localized area of the manifold;and (d) a plurality of outlet check valves positioned in a localizedarea of the manifold, which is separate from the localized area of themanifold where the inlet check valves are positioned.
 2. The apparatusof claim 1, wherein the inlet check valves are oriented such that fluidflows from the manifold to the reservoir during reservoir filling andfluid flow is prevented during reservoir draining and the outlet checkvalves are positioned such that fluid flows within the reservoir in thegeneral direction of from the inlet check valves to the outlet checkvalves, the outlet check valves being oriented such that the fluid flowsfrom the reservoir into the manifold during reservoir draining, andfluid flow is prevented during reservoir filling.
 3. The apparatus ofclaim 1, wherein the inlet check valve is an inlet duckbill check valve.4. The apparatus of claim 3, wherein the inlet duckbill check valve hasan elastomeric composition.
 5. The apparatus of claim 4, wherein theelastomeric composition of the inlet duckbill check valve is one or moreselected from the group consisting of polyolefin elastomer, hydrocarbonrubber elastomer, chlorosulfonated polyethylene elastomer, chlorinatedpolyethylene elastomer, neoprene, neoprene polychloroprene,perfluoroelastomers, fluoroelastomers, silicone rubber, syntheticrubber, and natural rubber.
 6. The apparatus of claim 1, wherein theoutlet check valve is an outlet duckbill check valve.
 7. The apparatusof claim 6, wherein the outlet duckbill check valve has an elastomericcomposition.
 8. The apparatus of claim 7, wherein the elastomericcomposition of the outlet duckbill check valve is one or more selectedfrom the group consisting of polyolefin elastomer, hydrocarbon rubberelastomer, chlorosulfonated polyethylene elastomer, chlorinatedpolyethylene elastomer, neoprene, neoprene polychloroprene,perfluoroelastomers, fluoroelastomers, silicone rubber, syntheticrubber, and natural rubber.
 9. The apparatus of claim 1 connected to apre-existing inlet/outlet conduit of a fluid reservoir.
 10. Theapparatus of claim 9, wherein the fluid reservoir contains a fluidselected from the group consisting of potable water, process water, andwastewater.
 11. The apparatus of claim 1, wherein the fluid reservoirhas a surface area and a height, the ratio of the surface area to theheight is greater than 2, and the apparatus for preventing stagnation isin a horizontal configuration, wherein the inlet/outlet conduit, themanifold, the inlet check valves, and the outlet check valves areapproximately in a plane parallel to the fluid surface.
 12. Theapparatus of claim 1, wherein the fluid reservoir has a surface area anda height, the ratio of the surface area to the height is less than 1 andthe apparatus for preventing stagnation is in a vertical configurationwherein the inlet/outlet conduit, the manifold, the inlet check valves,and the outlet check valves are approximately in a plane perpendicularto the fluid surface, the inlet check valves are located in an upperhalf of the fluid reservoir, and the outlet check valves are located ina lower half of the fluid reservoir.
 13. An apparatus for preventingstagnation in a fluid reservoir, which contains a fluid, comprising: (a)an inlet/outlet conduit; (b) a manifold which sequentially conveys thefluid to and from the inlet/outlet conduit; (c) a plurality of inletduckbill check valves; and (d) a plurality of outlet duckbill checkvalves, wherein the inlet duckbill check valves are positioned on themanifold and are oriented such that the fluid will flow from themanifold through the inlet duckbill check valves to the reservoir duringreservoir filling and fluid flow is prevented through the inlet duckbillcheck valves during reservoir draining; and wherein the outlet duckbillcheck valves are positioned on the manifold and spaced from the inletduckbill check valves to provide fluid flow within the reservoir in thegeneral direction from the inlet duckbill check valves to the outletduckbill check valves, the outlet duckbill check valves are orientedsuch that fluid flows from the reservoir through the outlet duckbillcheck valves into the manifold during reservoir draining, and fluid flowthrough the outlet duckbill check valves is prevented during reservoirfilling.
 14. The apparatus of claim 13, wherein the inlet duckbill checkvalves and the outlet duckbill check valves have an elastomericcomposition.
 15. The apparatus of claim 14, wherein the elastomericcomposition of the inlet duckbill check valves and the outlet duckbillcheck valves are independently one or more selected from the groupconsisting of polyolefin elastomer, hydrocarbon rubber elastomer,chlorosulfonated polyethylene elastomer, chlorinated polyethyleneelastomer, neoprene, neoprene polychloroprene, perfluoroelastomers,fluoroelastomers, silicone rubber, synthetic rubber, and natural rubber.16. The apparatus of claim 13 connected to a pre-existing inlet/outletconduit of a fluid reservoir.
 17. The apparatus of claim 16, wherein thefluid reservoir contains a fluid selected from the group consisting ofpotable water, process water, and wastewater.
 18. The apparatus of claim13, wherein the fluid reservoir has a surface area and a height, theratio of the surface area to the height is greater than 2 and theapparatus for preventing stagnation is in a horizontal configurationwherein the inlet/outlet conduit, the manifold, the inlet check valves,and the outlet check valves are approximately in a plane parallel to thefluid surface.
 19. The apparatus of claim 13, wherein the fluidreservoir has a surface area and a height, the ratio of the surface areato the height is less than 1 and the apparatus for preventing stagnationis in a vertical configuration wherein the inlet/outlet conduit, themanifold, the inlet check valves, and the outlet check valves areapproximately in a plane perpendicular to the fluid surface, the inletcheck valves are located in an upper half of the fluid reservoir, andthe outlet check valves are located in a lower half of the fluidreservoir.
 20. A method of preventing stagnation in a fluid reservoirfor storing liquids comprising the steps of: (a) introducing an influentliquid through an inlet/outlet conduit to a filling area of thereservoir through a manifold, which introduces the liquid to thereservoir through a plurality of inlet check valves; (b) withdrawing theliquid from a draining area of the reservoir through a plurality ofoutlet check valves on the manifold, wherein the draining area isremotely located from the filling area, such that the influent liquidmixes with the liquid in the reservoir, and the liquid in the reservoirgenerally flows from the filling area to the draining area; and (c)expelling the liquid from the draining area through the manifold and theinlet/outlet conduit.
 21. The method of claim 20, wherein the inletcheck valve is an inlet duckbill check valve.
 22. The method of claim20, wherein the inlet duckbill check valve has an elastomericcomposition.
 23. The method of claim 22, wherein the elastomericcomposition of the inlet duckbill check valve is one or more selectedfrom the group consisting of polyolefin elastomer, hydrocarbon rubberelastomer, chlorosulfonated polyethylene elastomer, chlorinatedpolyethylene elastomer, neoprene, neoprene polychloroprene,perfluoroelastomers, fluoroelastomers, silicone rubber, syntheticrubber, and natural rubber.
 24. The method of claim 20, wherein theoutlet check valve is an outlet duckbill check valve.
 25. The method ofclaim 24, wherein the outlet duckbill check valve has an elastomericcomposition.
 26. The method of claim 25, wherein the elastomericcomposition of the outlet duckbill check valve is one or more selectedfrom the group consisting of polyolefin elastomer, hydrocarbon rubberelastomer, chlorosulfonated polyethylene elastomer, chlorinatedpolyethylene elastomer, neoprene, neoprene polychloroprene,perfluoroelastomers, fluoroelastomers, silicone rubber, syntheticrubber, and natural rubber.
 27. The method of claim 20, wherein thefluid reservoir contains a fluid selected from the group consisting ofpotable water, process water, and wastewater.
 28. The method of claim20, wherein the fluid reservoir has a surface area and a height, theratio of the surface area to the height is greater than 2 and theapparatus for preventing stagnation is in a horizontal configuration,wherein the inlet/outlet conduit, the manifold, the inlet check valves,and the outlet check valves are approximately in a plane parallel to thefluid surface.
 29. The apparatus of claim 20, wherein the fluidreservoir has a surface area and a height, the ratio of the surface areato the height is less than 1 and the apparatus for preventing stagnationis in a vertical configuration, wherein the inlet/outlet conduit, themanifold, the inlet check valves, and the outlet check valves areapproximately in a plane perpendicular to the fluid surface, the inletcheck valves are located in an upper half of the fluid reservoir, andthe outlet check valves are located in a lower half of the fluidreservoir.